Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
  • F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
  • F03G7/06—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like
  • F03G7/061—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the actuating element
  • F03G7/0614—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the actuating element using shape memory elements
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
  • F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
  • F03G7/06—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like
  • F03G7/061—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the actuating element
  • F03G7/0614—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the actuating element using shape memory elements
  • F03G7/06143—Wires
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
  • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
  • F03G7/00—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for
  • F03G7/06—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like
  • F03G7/063—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the mechanic interaction
  • F03G7/0635—Mechanical-power-producing mechanisms, not otherwise provided for or using energy sources not otherwise provided for using expansion or contraction of bodies due to heating, cooling, moistening, drying or the like characterised by the mechanic interaction with several elements connected in series

Definitions

• the present disclosure relates generally to the area of actuators and actuation, and more specifically in one exemplary aspect, to an improved design for and methods of manufacturing and using an actuator apparatus which is actuated by a shape memory alloy (SMA) material.
• SMA shape memory alloy
• Actuator assemblies are well known in a variety of industries, including such common applications such as door locks, car vents, irrigation systems, and industrial applications, as well as in common household appliances mat include, without limitation, refrigerators, dishwashers and washing machines.
• a solenoid is a device that converts energy (e.g. electrical current, fluid pressure, etc.) into a linear actuation.
• An electromechanical solenoid typically comprises electrically conductive windings that are wrapped around a magnetic core. The windings produce a magnetic field when an electrical current is passed through it, thereby inducing the magnetic core to move.
• An actuator rod or other linkage element is coupled to the magnet, thereby actuating a parent device.
• Other types of "solenoids” also exist in the prior art and include devices such as pneumatic and hydraulic solenoids.
• a common limitation with regards to electromechanical solenoids is the fact that the actuating current is often generated via a series of batteries. Such batteries are often arranged in a series configuration, thereby adding the voltage of each cell while maintaining a common current through each.
• These solenoid actuators generally have comparatively large power requirements, and are often inefficient due to, inter alia, the internal resistance associated with the application of an electric current across the solenoid coils.
• electromechanical solenoids typically do not output a constant applied force as a function of actuation distance.
• an electromechanical solenoids actuation or stroke force decreases significantly over the length of the actuation. This is problematic, particularly in low power applications, in that electromechanical solenoid designs are generally "over-designed" for much of the actuating stroke length of the solenoid, i.e. more stroke force then is necessary is present throughout much of the stroke length of the solenoid, thereby decreasing the efficiency of the device.
• Electromechanical solenoids also are not particularly well suited for holding the actuator in an actuated state for long periods of time, as electrical current must be constantly applied. Many deleterious side effects result from holding an electromechanical solenoid in an actuated state for long periods of time, such as overheating, decreased stroke force as a function of time, and even electromechanical solenoid failure.
• such improved actuator apparatus would also address an unsatisfied need relating to so-called "green” technologies that enable the utilization of other green technologies (such as solar power), as well as reduce the volume of hazardous waste deposited in landfills by e.g., minimizing or eliminating the disposal of batteries that contain toxic metals such as lead, mercury and cadmium.
• the actuator apparatus includes a shape memory alloy (SMA) actuator apparatus having an actuator housing with a plurality of terminals coupled to the actuator housing.
• the SMA actuator apparatus includes an SMA filament coupled to respective ones of the terminals and a driver element configured to move when power is applied to the SMA filament, the driver element comprising an SMA protection apparatus.
• SMA shape memory alloy
• an ice dispenser apparatus comprised of a shape memory alloy (SMA) actuator is disclosed.
• the ice dispenser apparatus includes a base having an aperture disposed therein and a lid configured to open and close access to the aperture.
• An actuating element is coupled to the lid and an SMA actuator is configured to cause the lid to rotate about a rotational axis.
• a refrigerator vent apparatus comprising a shape memory alloy (SMA) actuator
• the refrigerator vent apparatus includes an SMA actuated rod comprising a dual action cam that is configured to open a refrigerator vent.
• SMA shape memory alloy
• an SMA driver element is disclosed.
• FIG. 1 is a perspective exploded view of an exemplary actuator assembly in accordance with the principles of the present disclosure
• FIG. 2 is a plot of force as a function of actuating displacement for both an actuator assembly in accordance with an exemplary embodiment of the present disclosure, and a prior art electromechanical solenoid actuator
• FIG. 3 is a top elevation view of a chassis assembly for use with, for example, the actuator assembly housing of FIG. 1 , in which a bistable diaphragm is used;
• FIG. 4 is a perspective exploded view of the exemplary actuator assembly of FIG. 1 with the chassis assembly reversed, in accordance with another embodiment of the present disclosure
• FIG. 5 is a perspective view of an exemplary dual actuator assembly in accordance with one embodiment of the present disclosure.
• FIG. 6 is a perspective view of an alternative configuration of an actuator assembly in accordance with another embodiment of the present disclosure.
• FIG. 6A is a perspective exploded view of the SMA filament assembly and driver element portion of the actuator assembly illustrated in FIG. 6;
• FIG. 6B is a perspective exploded view of the frame and pivot assembly portions of the actuator assembly illustrated in FIG. 6;
• FIG. 6C is a top view of the actuator assembly of FIG. 6, disposed in a pulling configuration
• FIG. 6D is a top view of the actuator assembly of FIG. 6, disposed in a pushing configuration
• FIG. 7 is a perspective view of another embodiment of an actuator assembly having an SMA filament protection feature, in accordance with the disclosure.
• FIG. 7A is a perspective view of the actuator assembly of FIG. 7 with the housing removed from view;
• FIG. 7B is a perspective view of the driver element with accompanying SMA filament protection feature for the actuator assembly of FIG. 7;
• FIG. 8 is a perspective view of an exemplary ice dispenser apparatus for a refrigerator mat utilizes the actuator assembly of FIG. 7;
• FIG. 9 is a perspective view of an exemplary refrigerator vent apparatus that utilizes an SMA actuated rod in accordance with the principles of the present disclosure.
• FIG. 9A is a sectional view taken along lines 9A - 9A of the vent apparatus of FIG. 9;
• FIG. 10 is a process flow diagram of an exemplary embodiment of a method of manufacturing the actuator assemblies of FIG. 1, and FIGS. 4 - FIG. 6 in accordance with the disclosure.
• filament refers to any substantially elongate body, form, strand, or collection of the foregoing, including without limitation drawn, extruded or stranded wires or fibers, whether metallic or otherwise.
• shape memory alloy or “SMA” shall be understood to include, but not be limited to, any metal that is capable of “remembering” or substantially reassuming a previous geometry. For example, after it is deformed, it can either substantially regain its original geometry by itself during e.g., heating (i.e., the "one-way effect") or, at higher ambient temperatures, simply during unloading (so-called “pseudo-elasticity”).
• shape memory alloys include nickel-titanium (“NiTi” or “Nitinol”) alloys and copper-zinc-aluminum alloys.
• the present disclosure provides an actuator apparatus having many advantages with respect to common prior art approaches, such as those previously described herein.
• the actuator apparatus of the disclosure includes an SMA filament that minimizes size and increases stroke length via a serpentine-like routing of the filament within the device. In this manner, the stroke length of the actuator can be increased without necessarily requiring an overall increase in size for the actuator assembly itself.
• the power consumption necessary to operate the actuator assembly is minimized, and reduced over prior art approaches.
• This is accomplished in one embodiment via the use of an SMA filament having an operating profile with a relatively flat stroke force as a function of stroke displacement
• stroke force drops off precipitously as a function of stroke distance, thereby requiring designers of these prior art electromechanical solenoids to design for worst case operating scenarios (thereby unnecessarily adding complexity and/or weight bulk to the design).
• an SMA actuator assembly configured in accordance with the present disclosure does not need to be "over- designed" throughout much of the stroke length, as was often the case in prior art implementations.
• embodiments of the present disclosure also enable the actuator assembly to remain in a fully actuated state, at a consistent stroke force, for appreciably longer periods of time, as compared with prior art actuator techniques.
• the actuator assembly of the disclosure is also fully reversible.
• Such a design enables the actuator to be used in push-based and pull-based actuator applications, while minimizing or eliminating the need to use customized actuator components, as well as eliminating the need for separate inventory management, part numbers, etc.
• Filament protection apparatus embodiments are also disclosed which protect, for example, SMA filaments from being damaged or broken when the underlying actuator apparatus becomes jammed or where movement of the actuator is otherwise prevented.
• the protection apparatus allows the filament to move, even in instances where the overall actuator apparatus can not move.
• SMA actuator apparatus that includes a steel/magnet button combination.
• Such an SMA actuator provides advantages over prior art configurations which utilized a torsion spring, for example, to keep a lid closed over the body of an ice dispenser apparatus.
• Such a configuration is desirable, as the force exerted by a steel/magnet button combination quickly dissipates as the two actuation force of the SMA filament only needs to be strong enough to break the initial magnetic coupling force.
• By lowering the amount of force necessary for the SMA filament to actuate the lid less stress is seen on the SMA filament, which increases product life.
• SMA rod actuator apparatus which in one embodiment includes a mechanism that not only allows for increased mechanical leverage, but also simultaneously allows for increased stroke length in applications such as refrigerator vents. Methods of operation and manufacturing associated with the aforementioned actuator apparatus are also disclosed.
• FIGS. 1 - 10 Exemplary embodiments of the apparatus and methods of the present disclosure are now described in detail with respect to FIGS. 1 - 10. It will be appreciated that while described primarily in the context of an actuator used to replace electro-mechanical actuators (e.g., electromechanical solenoids utilized in automobile door locks, household appliances, etc.), the disclosure is in no way limited to such applications, and may be applied to literally any application requiring actuator- induced movement of one or more components.
• electro-mechanical actuators e.g., electromechanical solenoids utilized in automobile door locks, household appliances, etc.
• Shaped memory alloy generally consists of a metal that is capable of "remembering” or substantially reassuming a previous geometry or physical condition. For example, after it is deformed, it can either substantially regain its original geometry by itself during e.g., heating (i.e., the "one-way effect") or, at higher ambient temperatures, simply during unloading (so-called “pseudo-elasticity”).
• shape memory alloys include nickel-titanium (“NiTi” or “Nitinol”) alloys and copper-zmc-aluminum alloys.
• Actuator Assembly Referring now to FIG. 1, an exemplary embodiment of an actuator assembly
• the actuator 100 comprises a tubular body 150, with the tubular body 150 encasing various elements of the actuator assembly 100 as described subsequently herein. These encased elements generally comprise what is known as the chassis assembly 102.
• the tubular body 150 in combination with the interchangeable threaded cap 120 and non-threaded cap 160, act in concert to protect the internal components of the assembly which ultimately provide the desired actuator-induced movement.
• the internal components that make up the chassis assembly include the driver element 130 along with the chassis 140, which in combination with the filament wire 180 are utilized to actuate the threaded shaft 110.
• an internal spring 194 is used to aid in returning the actuator assembly to its original state prior to actuation via the filament wire 180.
• the actuator assembly 100 also includes a trunnion element 170 which facilitates the movement of the driver 130 by acting as a pivot point within the chassis 140 for the movement of the filament wire 180, as will be described in more detail subsequently herein.
• the actuating movement of the threaded shaft is driven directly by the driver element 130 which is slidably coupled to the chassis 140.
• the driver element is in turn coupled to the wire filament 180.
• the filament wire 180 is adapted to, upon thermal activation, change physical shape. This is accomplished via the use of a shape memory alloy (SMA) material for the filaments.
• SMA shape memory alloy
• SMA alloys include for instance nickel-titanium (“NiTi” or “Nitinol”) alloys or copper-zinc-aluminum alloys.
• the SMA filaments used in the illustrated embodiments may have varying degrees of "memory". For example, in one variant, heating of a filament will cause its length to contract by a prescribed amount (e.g., 4% to 5% of total original length), but cooling back to its original temperature does not cause the filament to regain all of its original length, due to imperfect realignment within the material at the molecular/atomic level. Rather, a tensile stress must be applied to allow the material to regain its full original length, which is accomplished by way of a spring 194.
• Such alloys are well known to those of ordinary skill, and accordingly are not described further herein.
• the filament 180 is placed within the assembly in such a way mat the resultant change in shape (i.e., during thermal activation) causes a force to be applied to the driver element 130.
• This force causes the driver element 130 to slide along a guide rail present within the chassis so as to change from a first position to a second position.
• These alternating positions for the driver element 130 actuate the rod 110 within the tubular body, resulting in at least two distinct states for the assembly (i.e., "actuated” and "non-actuated”).
• the application of force to the driver element is relatively easy to maintain so long as thermal energy remains applied to the filament. This provides a distinct advantage over prior art electromechanical solenoid devices, which lose actuating force over time when kept in an actuated state.
• the exemplary SMA filaments When and while thermal energy is applied, the exemplary SMA filaments reduce themselves in length or contract.
• the application of thermal energy may be achieved in any number of known ways, including the application of a relatively small current through the filament, thereby heating the filament and altering its shape (length). Heat may be applied from an external source via conduction, convection, or even radiation as well.
• the filament 180 is positioned about the chassis 140 in a serpentine-like or doubled over shape. This shape permits the length of the filament 180 to be substantially greater without increasing the overall length of the actuator assembly 1 0, thereby increasing the stroke of the actuator assembly 100 significantly within the same form factor.
• the SMA filament were only to pass a single length of the tubular body so that the total length was, for example, one (1) inch in length, at a 4% length variation in an energized state, the total stroke for the filament would only be forty (40) mils, or forty-thousands of an inch (0.040 in.). Contrast this result with the design illustrated in FIG. 1 in which four (4) passes of the tubular body are made (resulting in a total length of approximately four inches in the present example), thus substantially increasing the total stroke to one- hundred sixty thousandths of an inch (0.160 in.).
• the securing mechanisms 190 of the filament are located on the same side of the actuator assembly chassis 140.
• the securing mechanisms 190 comprise crimp terminals specifically adapted for use with SMA filament, such as those described in co-owned U.S. Patent No. 7.650,914 filed June 22, 2006 and entitled "Apparatus & Methods for Filament Bonding & Manufacturing", the contents of which are incorporated herein by reference in its entirety.
• the power source is a direct current (DC) power source such as a battery or a common photovoltaic (e.g. a solar cell). While primarily contemplated with the use of a DC power source, it is appreciated that an alternating current (AC) power source could also be used (e.g., with a rectifier circuit or the like).
• DC direct current
• AC alternating current
• the trunnion element 170 illustrated in FIG. 1 acts as a pivot point for the filament as it expands and contracts.
• the trunnion 170 sits in a correspondingly sized feature resident within the chassis 140.
• the filament 180 which is wrapped around the periphery of the trunnion, causes the trunnion to angularly rotate about its axis to compensate for the shortening of the filament.
• the trunnion element 170 thus advantageously acts to relieve the stresses applied to the filament at this pivot point by minimizing abrasive stresses. Accordingly, use of a trunnion element extends the cycle life of the actuator assembly, and makes the assembly more robust and reliable in operation (due to, inter alia, reduced friction which may prematurely wear or even sever the filament).
• the trunnion element can be obviated in favor of a stationary post
• a stationary post can be utilized where the need for a more robust anti-wear mechanism in the actuator assembly 100 does not exist (e.g., in applications which are only required by design to be actuated one or a limited number of times), or where the design otherwise needs to be simplified by reducing the number of moving components such as for space, weight, and/or cost considerations.
• the stationary post in such cases will be smooth (e.g., highly polished), coated, lubricated, or otherwise made from a low friction material such as Teflon® or the like.
• the filament itself may be coated, lubricated, polished, etc. in addition to or in pace of the post, consistent with maintaining its desirable physical qualities and behavior under heating.
• the SMA filaments may be of varied or uniform thickness.
• the thickness of SMA filaments is determinative of the force associated with the filament's change in length, and with the length of time (latency) and amount of energy necessary to cause the change in the filament's length. Therefore, it is appreciated that a plurality of configurations having different numbers and or diameter of filaments 180 may be utilized consistent with the present disclosure to provide various desirable effects. For instance, in one variant, a plurality of small filaments disposed substantially in parallel are used to provide both low latency and high pull force, since (i) the forces of each individual filament are essentially additive, and (ii) the latency with each individual filament is low due to its small diameter. This advantageously provides the same level of force that a larger filament would, but without the greater latency associated therewith. However, such an arrangement requires an increase in electrical current over mat for a single filament, since each individual filament must be actuated.
• a number of different filaments with different thicknesses are used in parallel, thereby giving a distribution of force and latency.
• this latter variant results in the force applied by the filament being distributed over time, since each filament will contract (assuming the same start time for the application of current) over a different period of time, and with a different force level.
• the time and/or level of applied current can also be adjusted so as to create the desired force/time profile.
• Stranded filaments may also be used consistent with the disclosure.
• FIG. 2 one salient advantage of the SMA filament in the actuator assembly of FIG. 1 over prior art electromechanical solenoids is illustrated using a plot of applied force as a function of displacement More specifically, the plot 200 illustrated in FIG. 2 shows applied force as a function of displacement distance for both the actuator assembly of FIG. 1, and a comparable prior art electromechanical solenoid.
• the SMA actuator provides for a highly linear and constant stroke force throughout the entire stroke of the actuator, as indicated by the plot line 210. Compare the highly linear and constant stroke force of the SMA actuator assembly with the plot line 220 of a typical electromechanical solenoid, the latter in which the stroke force diminishes as a function of stroke distance.
• the applied force of the electromechanical solenoid drops precipitously as a function of displacement when a current is applied
• electromechanical solenoids typically are overdesigned throughout much of the stroke of the actuator (i.e., between the non-actuated distance and the full stroke distance 230).
• the electromechanical solenoid has to apply much more stroke force than is otherwise necessary throughout the remaining portion of the stroke distance.
• This "overdesign" of stroke force in other portions of the range or motion is typically accomplished by increasing electrical current flow to the solenoid coil (thereby increasing the generated magnetic field), which results in higher I 2 R losses, heat generation, and wasted energy. Accordingly, the use of SMA actuators allows for the minimization of an applied current to the SMA actuator assembly as applied current results in a constant stroke force throughout the stroke of the SMA actuator.
• an alternative embodiment of an SMA actuator 300 is shown, in which a current does not need to be applied to the SMA filament in order for the threaded rod 310 to remain in an actuated state.
• a bi-stable diaphragm 320 such as that described in co-owned and copending U.S. patent application Serial No. 12/539,521 filed August 11, 2009 and entitled “Multi-Stable Actuation Apparatus and Methods for Making and Using the Same", which claims priority to U.S. provisional patent application Serial No. 61/189,148 filed August 14, 2008 of the same title and to U.S. provisional patent application Serial No.
• the SMA actuator frame 340 accommodates at least two (2) distinct SMA wires 380, 382 each coupled to the driver element 330 and routed around respective trunnion elements 370, 372.
• Pulling SMA filament 380 applies a pulling force along an axis 332 to the threaded actuator rod 310 when a current is applied, while the pushing SMA filament 382 applies a pushing force along axis 332 to the threaded actuator rod 310 when a current is applied.
• the bi-stable diaphragm accordingly permits the threaded rod to remain in an actuated state upon completion of the application of current to the respective SMA filaments, with a subsequent application of current on an opposing SMA filament needed in order for the device to change states.
• Such a configuration is particularly advantageous in applications mat require the actuator to remain in a prolonged actuated state, and or where the overall power consumed by the SMA actuator needs to be minimized.
• FIG. 4 illustrates yet another advantage of the illustrated actuator assembly
• the reversed actuator assembly 400 includes all of the same features illustrated and discussed with regards to FIG. 1 (i.e., the actuator assembly components of FIG. 1 are included in the reversed actuator assembly 400 of FIG. 4), and also applies an identical stroke force in either configuration when the identical components are used.
• the chassis assembly 102 which includes the chassis 140, the driver element 130 and all the associated components used therewith, is reversed within the tubular body 150 such that the SMA filament, when actuated, pushes the threaded rod 110 from the threaded end cap 120. Contrast this with the embodiment illustrated in FIG. 1 in which the SMA filament, when actuated, pulls the threaded rod into the threaded end cap 120.
• the actuator assembly illustrated in FIG. 1 is reversible without requiring any additional specialized components for the reversed assembly 400.
• the illustrated actuator assembly can be implemented as either a push- based (expanding) or pull-based (contracting) actuator while utilizing all of the same components, thereby taking advantage of inter alia economies of scale when manufacturing, stocking, and distributing the components for both the pull-based and push-based SMA actuators.
• FIG. 5 illustrates a dual SMA actuator assembly 500 in accordance with the principles of the present disclosure.
• the dual SMA actuator assembly illustrated includes a dual actuator tubular body 550 which houses two (2) of the chassis assemblies such as that shown in, for example, FIGS. 1 and 4.
• the dual SMA actuator assembly also includes a dual actuator end cap 560 along with a dual actuator threaded end cap 520. Accordingly, in one configuration, the top threaded rod 510 may be used for push-based actuation, and the bottom threaded rod 512 used for pull- based actuation. In this manner, the actuator assembly 500 can actuate in two (2) different directions.
• top and bottom threaded rods 510, 512 may actuate in the same direction; i.e., be bom pull-based or alternatively both push-based with regards to actuation. Accordingly, the applied stroke force for the actuator assembly 500 will effectively be doubled assuming the units are energized simultaneously. Furthermore, three (3) or more threaded rods could be implemented in an alternative embodiment (not shown) which permits additional flexibility or permutations to those alternatives discussed above.
• tubular body 550 and end caps 520, 560 are shown in FIG. 5, it is envisioned that the tubular body 150 and end caps 160, 120 of FIG. 1 may alternatively held together via a bracket, etc. (not shown) so that the dual actuator functionality discussed with regards to FIG. 5 can be implemented without necessitating any customized parts (with the exception of the aforementioned bracket) outside those components illustrated in FIG. 1.
• the two (or more) actuators in the tandem configuration may be oriented in reverse or alternating fashion; e.g., one having its rod projecting out one end of the assembly, and one with its rod projecting out the other end.
• the actuator 600 comprises a chassis 660 that houses various elements of the actuator assembly.
• the elements housed within the chassis generally comprise those which ultimately provide the actuating movement for the assembly, as will be described in more detail subsequently herein.
• the internal components that provide the actuator-inducted movement include the driver element 620 along with the pivot assembly 670, which in combination with the filament wires 680, 682, 684 (see FIG. 6A) are utilized to actuate the shaft 610.
• a compression spring 694 is used to aid in returning the actuator assembly to its original state prior to actuation.
• the compression spring is sandwiched between the driver element and the spacer element 630, with the distance between the driver element and spacer element defining the non-actuated compression spring length.
• the loop filament is thus similarly heated, resulting in SMA contraction and thereby further actuating the driver element towards the pivot assembly. Accordingly, the amount of travel obtained by SMA actuation is not only the amount of contraction seen in both the upper and lower SMA filaments, but the added actuation distance obtained by the mechanical advantage provided by the pivot assembly. Increasing the actuator stroke length is often desirable, in that the increased total stroke permits a wider array of actuator end applications for the actuator assembly 600. In the illustrated embodiment, approximately 1.2 Ib-f is required to initiate movement of the threaded shaft 610.
• the actuator assembly is illustrated with the chassis, terminals, and pivot assembly removed from view so mat other features of the actuator assembly are more readily visible.
• the driver element 620 of this embodiment includes a guide slot 622 which facilitates lateral movement along the chassis, as well as a filament routing channel 624 used for routing the loop filament 680 around the front portion of the driver element.
• the spacer element 630 also includes a respective slot 632 configured to be positioned in cooperation with a corresponding feature on the chassis.
• the filament assembly 681 includes a loop filament 680 mat starts and ends at the same end of the actuator assembly.
• the filament assembly also includes upper 682 and lower 684 straight line filaments that are electrically coupled to the loop filament via jumper filaments 686. These jumper filaments are utilized to facilitate the transmission of electrical current between the straight line filaments 682, 684 and the loop filament 680.
• the actuating movement of the shaft is driven by an electrical power source connected to conductive terminals 692. These conductive terminals are electrically coupled to the filaments.
• the driver element 620 is in turn coupled to the lower filament 680 with the lower filament being in electrical communication with the upper filament via the conductive pivot shuttle 676 (see FIG. 6B).
• the filament wires 680, 682 are adapted to, upon thermal activation, change physical shape. This is accomplished via the use of a shape memory alloy (SMA) material for the filaments.
• SMA alloys include, for instance, nickel-titanium (“NiTi" or “Nitinol”) alloys, copper-zinc-aluminum alloys, etc.
• the SMA filaments used in the illustrated embodiments may have varying degrees of "memory" as discussed previously herein. A tensile stress must therefore be applied in such cases if the material is required to regain its full original length; this is accomplished by way of a spring 694 in the illustrated embodiment.
• Such alloys are well known to those of ordinary skill, and accordingly are not described further herein.
• each of the ends of the respective filaments in the filament assembly have crimping elements 690 secured thereto. These filament crimping elements include crimp features (such as, e.g., those described in co-owned U.S. Patent No. 7,650,914, previously incorporated herein).
• the crimping elements also include a hoop feature 696 that is configured to fit around respective features on the pivot shuttle (FIG. 6B) and terminal clip 698 (FIO. 6B).
• the shaft 610 also includes a polished portion 612 that facilitates actuation movement by reducing the amount of friction between the shaft and respective features on the spacer 630 and the through-hole 674 located on the trunnion 672 (FIG. 6B). These features are positioned in a housing, which includes a housing cap 602 as shown in FIG. 6A.
• the pivot assembly is formed from a trunnion 672 that has a through-hole 674 formed therein.
• the through-hole is sized so that the polished surface of the threaded shaft (not shown) can freely travel therein during actuation.
• the trunnion acts as a pivot point or fulcrum for the pivot shuttles 676 that gives the actuator assembly its mechanical advantage.
• the trunnion includes bom an upper and a lower pivot shuttle assembly.
• Each pivot shuttle assembly includes two (2) shuttles 676 that are joined via star pins 675.
• the pivot shuttle assembly also includes a pivot cap 677 that helps position the pivot shuttle assembly within the body 604.
• the body 604 houses and protects the actuating components of the actuator assembly, and is closed on the ends by end cap 606 and threaded end cap (602, FIG. 6A).
• the external structure of the actuator assembly also includes a rubber band 608 or other such mechanism which is used for securing the terminals to the body of the actuator assembly.
• Electrical terminals 692 provide the electrical current necessary to provide power to the actuator assembly.
• the electrical power provided via the electrical terminals may be provided from any number of conventional means, including low power alternative power sources (e.g. photovoltaics).
• the SMA filaments illustrated in the actuator assembly of FIGS. 6 - 6B may be of varied or uniform thickness, as previously discussed with respect to the embodiment of FIG. 1.
• the thickness of SMA filaments is determinative of the force associated with the filament's change in length, and with the length of time (latency) and amount of energy necessary to cause the change in the filament's length. Therefore, it is appreciated that a plurality of configurations having different number and diameter of filaments 680, 682 may be utilized consistent with the present disclosure to provide various desirable effects. For instance, in one variant, a plurality of small filaments disposed substantially in parallel are used to provide both low latency and high pull force. In another variant, a number of different filaments with different thicknesses are used in parallel, thereby giving a distribution of force and latency. The time and/or level of applied current can also be adjusted so as to create the desired force/time profile.
• FIGS. 6C and 6D two (2) differing configurations of the actuator assembly 600 are shown.
• FIG. 6C illustrates the actuator assembly of FIGS. 6 - 6B in a "pulling" configuration, with the threaded end cap 602 positioned at the opposite end of the pivot assembly.
• FIG. 6C also illustrates an exemplary positioning of the rubber band 608 so mat it retains the terminals 692 next to the body 604.
• FIG. 6D illustrates the actuator assembly in a "pushing" configuration, with the threaded end cap 602 now positioned on the same side of the body as the pivot assembly.
• a salient advantage of the illustrated actuator assembly of FIGS. 6 - 6D namely its ability to be used in both "pull” and “push” configurations while using identical components.
• FIG. 7 illustrates an alternative SMA actuator assembly 700 with an SMA protection apparatus installed therein.
• the SMA actuator assembly illustrated in FIG. 7 is positioned within a housing 710 mat has two (2) housing mounts 712 (see also FIG. 8).
• SMA protection apparatus described herein could be used in a wide variety of actuator assembly configurations, such as that described with respect to FIGS. 1, and 3 - 6, with the configuration shown in FIG. 7 merely being illustrative.
• the actuator assembly of FIG. 7 includes a driver element 720 that is coupled with an end element 714.
• the driver element is in turn actuated by the contraction of the SMA filament 740 that is connected to powered terminals 730, 732 (FIG. 7A).
• FIG. 7A FIG.
• FIG. 7A illustrates the SMA actuator assembly with the housing removed from view, so that the internal components of the actuator assembly are more readily visible. Specifically, the serpentine routing of the SMA filament 740 with its ends connected to the first 730 and second terminals 732 is now readily visible. In addition, the routing of the SMA filament around the ends of the driver element within the routing channels 722 can now be seen.
• the driver element 720 consists of a primary shaft 724 and a secondary shaft 760 that has a primary compression spring 750 and a secondary compression spring 752 associated with the primary and secondary shafts, respectively.
• the driver element includes an actuator element 762 that receives the element to be actuated.
• the SMA filament is heated which causes the filament to contract
• the contraction of the SMA filament causes the driver element to actuate along the primary shaft 724, thereby causing the primary compression spring 750 to compress.
• the element e.g. offset actuator element 852, FIG. 8
• the actuator element cavity 762 can become stuck, which can place a significant amount of stress on the SMA filament.
• the secondary shaft 760 and secondary compression spring 752 are configured to prevent the SMA filament from breaking during these instances where the element coupled to the driver element becomes stuck. Specifically, during instances where the element to be actuated can not move (or requires an excessive amount of force to move), the actuator element 762 will move freely within the driver element cavity 726. During normal operation, the actuator element is held against the first stop element 728 by the secondary compression spring which is held in tension between the first stop element and the second stop element 729. In the exemplary illustrated configuration, the spring constant associated with the secondary compression spring governs the amount of force required to enable the SMA protection apparatus to be actuated to protect the filament.
• the actuator element 762 moves relative to the movement associated with the driver element, thereby protecting the SMA filament from stresses that can result in damage to or even complete failure of the SMA filament.
• the ice dispenser apparatus includes a base 840, and a lid 830 that opens by rotating about the rotational axis 810.
• the actuating element 850 of the lid includes an offset actuator element 852 that, when driven by the actuation apparatus 700, causes the lid to open.
• the primary compression spring (750, FIG. 7B) then causes the lid to close upon the removal of electric current from the SMA filament in the actuation apparatus.
• the exemplary ice dispenser apparatus also includes a steel button 820 configured to operate in conjunction with a button magnet 822.
• the button magnet is positioned on or within the lid, while the steel button is positioned inside the base of the ice dispenser apparatus, although it is appreciated that the positioning of these respective components could be reversed or otherwise adjusted or varied.
• combinations which utilize other magnetic materials, whether heterogeneous as in the present instance, or homogenous are also envisioned with the steel/magnet button combination merely being exemplary.
• the use of the steel/magnet button provides advantages over prior art configurations which utilized a torsion spring to keep the lid closed over the body of an ice dispenser apparatus.
• Such a configuration is not necessarily desirable when the actuation for the ice dispenser is being provided by an SMA filament.
• Magnets work in an opposite manner. Specifically, the force applied by a magnet generally dissipates in an inverse squared relationship as the distance from the magnet increases.
• the actuation force of the SMA filament only needs to be strong enough to break the initial magnetic coupling force, as the force required to open the lid will dissipate rapidly as the lid separates from the base.
• the amount of force necessary for the SMA filament to actuate the lid less stress is seen on the SMA filament.
• the amount of cycles that can be expected for a given SMA filament will increase, resulting in among other things a longer product life.
• a prior art ice dispenser with a torsion spring requires 4.41bf (pounds-force) in order to fully open lid.
• FIG. 8 only necessitates a minimal force (.35 lbf) in order to open the lid of the ice dispenser apparatus.
• a refrigerator vent apparatus 900 that utilizes an SMA actuated rod 910 in order to open (and close) the refrigerator vent 930 is shown and described in detail.
• the SMA filament (not shown) in the illustrated in FIG. 9 actuates a dual action cam 920 that in turn opens a refrigerator vent. Because of conditions within the refrigerator, the vent can periodically stick due to ice buildup, often requiring much more force to initially open the vent than is otherwise required to complete the opening cycle for the vent when unimpeded.
• the rod illustrated in FIG. 9 advantageously reduces the amount of work required to open the vent door.
• the dual action heart shaped cam illustrated in FIG. 9 works to keep the door open after actuation without necessitating that the SMA filament remain energized.
• the operation of the SMA actuated rod 910 of FIG. 9 can better be seen.
• the lower finger 914 of the rod Prior to actuation, the lower finger 914 of the rod is in contact (or close proximity) with the vent door 930.
• the upper finger 912 of the rod is spaced further from the vent door 930 than the lower finger prior to actuation.
• the SMA filament When a current is applied to the SMA filament (not shown), the SMA filament will shrink, causing the rod to be pulled towards the vent door.
• the lower finger of the rod being spaced at a farther distance from the axis of rotation 932 than the upper finger, will engage the vent door first Because the lower finger is spaced further from the axis of rotation 932 man the upper finger, the lower finger possesses a mechanical advantage over the upper finger, allowing the rod to break any sticking mat may have resulted from icing on the vent door. At a predetermined point past the point where the vent door might stick, the upper finger engages the vent door. As the upper finger is closer to the axis of rotation man the lower finger, the upper finger can open the vent further than the lower finger given the same amount of SMA filament shrinkage. In addition, because the upper finger does not engage the vent door until past the sticking point during an icing condition, the amount of force required to open the vent is significantly lower.
• the SMA actuated rod could be coupled to any of the actuator embodiments illustrated in FIGS. 1, and 3 - 6.
• such an embodiment can also incorporate the filament protection apparatus as illustrated in FIGS. 7 - 7B so as to ensure that the SMA filament would not break should an excessive amount of ice build up around the refrigerator vent (thereby preventing the vent from opening).
• the vent door could incorporate the steel/magnet button combination illustrated and described with respect to FIG. 8 in some embodiments.
• FIG. 10 an exemplary embodiment of a method 1000 of manufacturing an SMA actuator assembly (such as those shown in FIGS. 1 and 3 - 6) is shown and described in detail.
• the actuator components for use in the actuator assembly are formed.
• the components may be formed from any number of suitable manufacturing methodologies that would be readily apparent to one of ordinary skill given the present disclosure.
• the tubular body 150 and end caps 120, 160 are in one implementation manufactured from a suitable polymer (plastic) material using standard injection molding techniques.
• the injection molded process could be substituted with a die-cast process, or use of a machined metal component
• many of the components used in the chassis assembly are also, in an exemplary embodiment, manufactured from a polymer based material using an injection molding process.
• the chassis 140, trunnion element 170 and driver element 130 are all well suited for the injection molding process, which reduces cost and maintains low component weight for comparatively high strength.
• the filament securing elements 1 0 and electrical terminals 192 are preferably manufactured using standard progressive stamping manufacturing dies in order to minimize costs in volume production, while the internal spring 194, threaded rod 110 and SMA filament wire 180 are manufactured using well-known methodologies appreciated by those of ordinary skill given the present disclosure.
• the chassis assembly 102 is assembled by crimping the SMA filament 180 to respective ends of the filament securing elements 190.
• the trunnion element 170 is inserted into its respective receptacle feature on the chassis 140.
• the driver element and spring 194 are also inserted into the chassis, and the SMA filament 180 is subsequently routed around the driver element and trunnion element, respectively, in order to provide the mechanism for actuations.
• the filament securing elements 190 in combination with the electrical terminals 192 are then inserted into the chassis to complete the chassis assembly.
• step 1006 it is determined whether the chassis assembly that was assembled in step 1004 will be utilized as either a push-based or pull-based actuator. Subsequently, at step 1008, the chassis assembly is inserted into the body ISO consistent with the decision made at step 1006. The end caps 120, 1 0 and the threaded rod 110 are then disposed on the tubular body in a manner consistent with the decision reached at step 1006.
• step 1010 the decision to reconfigure the SMA actuator assembly is made. If it is to be reconfigured, then the opposite actuator configuration to mat previously chosen is selected at step 1006 and the actuator assembly is subsequently disassembled and re-assembled into the reconfigured SMA actuator assembly configuration. If not, then the SMA actuator assembly is installed and utilized in its end application.

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• Engineering & Computer Science (AREA)
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• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Transmission Devices (AREA)
• Vehicle Body Suspensions (AREA)

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• 2012
  • 2012-10-26 EP EP12842905.7A patent/EP2771969A4/de not_active Withdrawn
  • 2012-10-26 CN CN201280063898.6A patent/CN104040871B/zh not_active Expired - Fee Related
  • 2012-10-26 WO PCT/US2012/062283 patent/WO2013063511A2/en not_active Ceased
  • 2012-10-26 US US13/662,210 patent/US9206789B2/en active Active
• 2015
  • 2015-03-27 US US14/671,823 patent/US9790930B2/en not_active Expired - Fee Related

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